A method of continuously casting metals

ABSTRACT

THIS INVENTION IS TO CAST METALS CONTINUOUSLY BY USING A SUBSTANCE WHICH IS HIGHER IN THE SPECIFIC GRAVITY BUT LOWER IN THE MELTING POINT THAN A METAL TO BE CAST AND WHICH HAS A   PROPERTY OF PRODUCING NO ALLOY OR COMPOUND WITH THE MOLTEN METAL BY USING A HORIZONTALLY SET CHANNEL TYPE CASTING MOLD.

United States Patent Inventor 'latsuo Kuratorni 4-2-18, Harnatake, Chigasaki Kanagawa Prefecture, Japan Appl. No. 802,124 Filed Feb. 25, 1969 Patented June 28, 1971 Priority Nov. 7, 1968 Japan 43/80971 A METHOD OF CONTINUOUSLY CASTING METALS 3 Claims, 3 Drawing Figs.

Int. Cl. B2211 23/00 Field of Search 164/81, 82,

Primary Examiner-J. Spencer Overholser Assistant Examiner.lohn E. Roethel Attorney0tto John Munz ABSTRACT: This invention is to cast metals continuously by using a substance which is higher in the specific gravity but lower in the melting point than a metal to be cast and which has a property of producing no alloy or compound with the molten metal by using a horizontally set channel type casting mold.

PATENIED Jun2 8 [an INVENTOR 'lA'l'SlK) KURA'I'OMI ATTORNEY A METHOD OF CONTINUOUSLY CASTING METALS This invention relates to a method and apparatus for continuously casting metals.

There are used today vertical-type and curved-type apparatus for continuously casting metals. However, such apparatus are so large in the total height that a high constructing cost is required and the danger is also high.

An object of the present invention is to provide a method for continuously casting metals which is low in the constructing cost and can be operated safely by horizontally setting the entire casting apparatus.

A further object of the present invention is to provide a continuous casting apparatus which is high in the economy and safety by horizontally setting the entire casting apparatus.

The apparatus of the present invention is substantially as mentioned below. That is to say, it is formed of a horizontally set long tank, cooling devices and heating devices set within the tank, a melt pouring chamber provided near one end of the tank and a channel-type or three-surface casting mold provided with a cooling water jacket and made in the form of a channel connected directly to an opening made in the lower part of the side of the molten metal pouring chamber and an outlet provided at the other end of the tank so as to connect them. A melt (which shall be referred to merely as a melt hereinafter) of a metal or compound which is higher in the specific gravity than the metal to be cast is kept in the tank of such apparatus, the lower part of the above-mentioned molten metal pouring chamber and the channel-type casting mold are set so as to be dipped in the melt, a molten metal to be cast (which shall be referred to merely as a molten metal) is continuously fed into the molten metal pouring chamber and, while the above-mentioned molten metal flows as floated horizontally on the above-mentioned melt toward the outlet of the tank while in contact with the inside surface of the ceiling within the above-mentioned channel-type mold, the molten metal is cooled with cooling water in the jacket of the abovementioned channel-type mold through the mold and is also cooled through the melt by the cooling devices provided in the tank so that the molten metal may be coagulated on the surfaces from the four sides and the metal in a half-coagulated state leaving an uncoagulated part in the center part is horizontally pulled continuously out of the tank and is then directly cooled to be a continuous casting of the metal as one feature of the present invention. Further, as a melt to be used to float the molten metal is used such substance which is not only higher in the specific gravity than the metal to be continuously cast but also will not evaporate at the casting temperature of the molten metal, is lower in the melting point than the metal to be cast and has a property of producing no alloy or compound with the molten metal as another feature.

In the accompanying drawings:

F IG. 1 is a vertical sectional view of an apparatus for working a method for continuously casting metals according to the present invention;

FIG. 2 is a sectional view on line [H1 in H0. 1;

FIG. 3 is a sectional view on line lll-lll in FIG. 1.

ln the drawingsQl is a tank forming a body part of the present apparatus, 2 is a molten metal pouring chamber which is provided near the front'wall at one end of the tank and into which a molten metal to be continuously cast is continuously fed and 3 is a continuous casting mold which is fixed directly to an opening 4 made in the lower part of the side of the above-mentioned molten metal pouring chamber so as to enclose the opening and is connected at the other end to an outlet 5 provided at theother end of the tank. The casting mold 3 is a passage-shaped mold of a channel-shaped cross section consisting of three surfaces both sidewalls and a ceiling part and opened toward the bottom of the tank. Both sidewalls of this channel-type mold are dipped in a melt contained in the tank, the opening 4 in the lower part of the molten metal pouring chamber is made an inlet and the opening 5 in the rear wall of the tank is made an outlet so as to form a casting chamber. As the molten metal pouring chamber 2 and the channel-type mold 3 are connected with each other as mentioned above, when a molten metal is continuously fed into the molten metal pouring chamber 2, the molten metal will float on the melt and will continuously flow as enclosed with the surface of the melt and the inside surfaces of the channel-type mold toward the outlet of the mold. Therefore, if the level 7 of the melt is kept higher than the back surface 6 of the ceiling part of the channel-type mold, a buoyancy will be produced due to the difference between the heights and the difference between the specific gravities of the molten metal and the melt so that the molten metal may be pushed against the inside surface of the ceiling part of the channel-type mold. V

The ratio of the height y from the contact surface which is the lower surface of the molten metal floating in direct contact with the melt in the tank to the level of the melt in the tank to the height x from the above-mentioned contact surface of the molten metal and the melt to the level of the molten metal in the molten metal pouring chamber is inversely proportional to the ratio of the specific gravity of the melt to the specific gravity of the molten metal. Therefore, the level 13 is the molten metal pouring chamber of the molten metal which is lower in the specific gravity than the melt will be arranged in a position higher than the level 7 in the tank of the melt which is higher in the specific gravity than the molten metal.

As both sidewalls and the ceiling of the channel-type casting mold 3 are of a cooling water jacket structure 8, the molten metal in the channel-type castingmold is cooled on both sides and the upper surface through the walls of the channel-type mold by the cooling water in the jacket. On the other hand, cooling devices 9 for cooling the melt in the tank are set in proper positions within the tank so that the coagulation heat generated in case the molten metal floating on the melt coagulates may be taken away through the melt. Therefore, the mo]- ten metal floating within the channel-type mold is cooled on the four surfaces of its both side surfaces and upper and lower surfaces and begins to coagulate on the four surfaces while it flows through the mold toward the outlet and the coagulated layer gradually increases its thickness. The molten metal is thus enclosed with the above-mentioned coagulated layer but reaches the outlet of the tank while it is not yet coagulated in the center part as shown with a dotted line 10, is pulled horizontally and continuously out of the tank, is cooled directly by the cooling apparatus 11 so as to be coagulated to the center part and is continuously fed to the next step. Within the tank are provided not only the above-mentioned cooling devices 9 but also devices 12 for heating the melt so that the raw material of the melt may be heated to be melted in advance before the operation starts and the temperature of the melt during the operation may be kept at a proper value. The amount of feed of the molten metal is so determined that the level 13 of the molten metal within the molten metal pouring chamber 2 may be kept higher than the position of the lower surface 6 of the ceiling of the mold and the head due to the difference between their heights may act as a feedhead on the molten metal in the mold. 14 is a space forming the upper part of the tank and is filled with a reductive or inert gas so that the melt and molten metal may be prevented from being oxidized. (No gas feeding port is illustrated.) 15 is a movable door provided at the outlet of the tank and its height is made variable so that the melt and molten metal may not overflow.

Examples of the present invention shall be explained.

EXAMPLE 1 This example is of the case of continuously casting iron or an iron alloy which will produce no alloy or compound with lead. In the explanation of this example, the above-mentioned iron or iron alloy shall be referred to merely as iron. In the case of continuously casting iron, a continuously casting apparatus according to the present invention explained above is used and as a melt to be used to float molten iron is used a melt of lead. ln starting the operation, first solid lead is put into the tank,- is heated to be melted by using the heating devices provided in the tank, the level of this lead melt is kept at a height substantially equal to the height of the upper surface of the ceiling of the channel-type casting mold, the temperature of this lead melt is maintained at 500 C. and then molten iron is continuously fed at a specified volume of flow from a tundish. As the lead melt is used as a melt to float molten iron, the ratio of the height from the contact surface of the molten iron floating in direct contact with the lead melt and said lead melt to the level in the tank of the lead melt to the height from the contact surface of the molten iron and lead melt to the level in the molten metal pouring chamber of the molten iron is inversely proportional to the ratio of 1 L3 which is the specific gravity of the lead melt to 6.9 which is the specific gravity of the molten iron. Therefore, the molten iron floats on the lead melt.

Thus the molten iron continuously fed into the molten metal pouring chamber continuously moves as floated on the lead melt through the channel-type mold. Further, as the molten iron is subjected a buoyancy from the lead melt, the molten iron remains in contact on both sides and the upper surface respectively with the three surfaces inside the channel-type mold and on the lower surface with the surface of the lead melt.

Therefore, the molten iron continuously flow while being cooled on the four surfaces through the respective walls of the channel-type casting mold and the lead melt toward the outlet of the tank. in starting such continuous casting operation, a plug member (not illustrated) is inserted into the outlet part of the channel-type mold and is kept fixed until the depth of the molten iron in the mold reaches a fixed depth. At the same time as the depth of the molten iron in the channel-type mold reaches a fixed depth, the coagulation of the molten iron coagulated and bonded on the end surface of said plug member is continuously pulled out of the tank. The velocity of this pulling out is made to match the coagulating velocity of the molten iron in the channel-type mold. After the continuous casting operation is thus started, the coagulation of the molten iron is continuously pulled out of the rear end of the mold through the outlet. While the molten iron continuously fed into the channel-type casting mold from the molten metal pouring chamber moves continuously through the mold, it is cooled on the four surfaces through both sidewalls and the ceiling of the casting mold and the lead melt and begins to coagulate on the outer peripheral part. As the coagulation has an uncoagulated part remaining in the center part of it near the outlet of the tank, it is continuously pulled out of the tank as kept horizontal and cooling water is jetted on it so that the uncoagulated part remaining in the center part may coagulate to produce a continuous casting of iron.

In the process wherein the molten iron is cooled to coagulate with the channel-type casting mold, as the molten iron floats in direct contact on the lower surface with the lead melt, it coagulates as pushed against the respective surfaces inside the mold. Therefore, the coagulation of the molten iron pulled out of the channel-type mold keeps a correct form on both sides and the uppersurface of it and, as it has coagulated on the lower surface in direct contact with the surface of the lead melt kept at a fixed level, it has a flat smooth lower surface.

On one hand, as this coagulation continuously moves as floated on the lead melt, the coagulation of the molten iron is not subjected to any resistance and is not hurt by friction.

On the other hand, if the amount of feed of the molten iron into the molten metal pouring chamber is adjusted so as to maintain the level of the molten iron in the molten metal pouring chamber to feed the molten iron into the channel-type mold to be higher than the lower surface of the ceiling part of the mold, the liquid pressure of the molten iron due to the head by the difference between the height of the level of the molten iron in the molten metal pouring chamber and the height of the lower surface of the ceiling of the mold will act so that the molten iron within the mold may coagulate while being subjected to the same action as of a feedhead in the generally practiced casting.

In' the case of coagulating, the molten iron as floated on the surface of the lead melt as explained above, the molten iron and lead melt will produce no alloy or compound and therefore the continuous cast iron will not be stained with lead but will become a continuous iron casting of any desired quality.

EXAMPLE 2 Example 2 is of the case of continuously casting aluminum or an aluminum alloy which will produce no alloy or compound with lead or at least one iodide among calcium iodide and lithium iodide. In the explanation of this example, the aluminum or aluminum alloy to be continuously cast shall be referred to merely as aluminum.

In continuously casting aluminum, as a melt to be used to float, cool and coagulate molten aluminum is used one or more iodides selected from among lithium iodide and calcium iodide or the selected iodide as mixed with another halide in a molten state. Such iodide will produce no alloy or will not chemically react with aluminum. The specific gravity of the melt of such iodide is 4.061 in the case of lithium iodide and 3.956 in the case of calcium iodide whereas that of the melt of aluminum is 3.98. Further, the melting point of such iodide is 446 C. in the case oflithium iodide and 575 C. in the case of calcium iodide and is lower than the melting point of 660 C. of aluminum. Further, the boiling point of such iodide is 1.l C. in the case oflithium iodide and 718 C. in the case of calcium iodide. The temperature of molten aluminum to be cast continuously is less than 700 C. except special alloys. Therefore, there is no trouble in floating molten aluminum on the melt ofsuch iodide.

As evident from the above-mentioned explanation, as the molten metal within the channel-type casting mold is in contact on both sides and the upper'surface with the respective inside surfaces of the mold and on the lower surface with the upper surface of the melt, the casting pulled out of the channel-type mold has no irregularities but is flat on the surface and is kept constant in the dimensions of the cross section. Therefore, not only there is no trouble in carrying out the subsequent operation but also, as the casting floats on the upper surface of the melt and there is no mechanical friction between its bottom surface and the upper surface of the melt, the power required to continuously pull the casting out of the mold may be small and the mold and tank will not be hurt. Further, as all the above-mentioned steps proceed along the same horizontal surface, no high structure is required, the safety of the operation is very high and the construction cost may be small. Therefore, it can be said that the casting made by the continuously casting method and apparatus of the present invention is high in the economy and safety.

lclaim:

l. A method for continuously casting metals comprising steps of keeping in a tank of melt of a metal or compound which is higher in the specific gravity than a molten metal to be continuously cast, will produce no alloy or compound with the molten metal, will not evaporate at the temperature of the molten metal and will melt at a temperature lower than the temperature of the molten metal, dipping in the melt in the said tank a channel-type casting mold which is formed of both sidewall parts and a ceiling part, is opened in the bottom part, is connected at one end with a molten metal pouring chamber and is opened at the other end outward at an outlet provided in the bottom part on one side of the tank, continuously feeding the molten metal into the channel-type casting mold through the molten metal pouring chamber, keeping the level of the molten metal within the above-mentioned molten metal pouring chamber always higher than the lower surface of the ceiling of the channel-type casting mold so that the molten metal within the casting mold may act as a feedhead, adjusting the level of the melt so that the level of the melt within the tank enclosing the casting mold may be higher than the upper surface of the melt supporting the molten metal within the casting mold so as to produce a force for the upper surface of the molten metal within the casting mold to push up directly against the lower surface of the ceiling of the mold, cooling and coagulating from the periphery the molten metal moving continuously through the casting mold toward the outlet and 2. A method according to claim 1 wherein said melt is of lead when said molten metal is iron.

3. A method according to claim 1 wherein said melt is of lead or an iodide selected from a group consisting of calcium completely cooling outside the casting pulled horizontally and 5 iodide and lithium iodidecontinuously out of the mold. 

